AutoCodes – GMC – P1194 2016 GMC Sierra

P1194 2016 GMC Sierra Code - O2 Low Reference Circuit High Voltage (NOx Sensor 1)

Quick Answer

The Nitrogen Oxides (NOx) sensors are part of the selective catalytic reduction system, a device used to reduce NOx emission on diesel engines. Common causes include Faulty Nitrogen Oxides (NOx) Sensor, Nitrogen Oxides Sensor harness is open or shorted, Nitrogen Oxides Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1194 2016 GMC Sierra indicates O2 Low Reference Circuit High Voltage (NOx Sensor 1).
Common causes: Common causes include Faulty Nitrogen Oxides (NOx) Sensor, Nitrogen Oxides Sensor harness is open or shorted, Nitrogen Oxides Sensor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 169

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Mar 24, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1194 2016 GMC Sierra Description

The Nitrogen Oxides (NOx) sensors are part of the selective catalytic reduction system, a device used to reduce NOx emission on diesel engines. There are two NOx sensors, one placed upstream of selective catalytic reduction, to measure inlet NOx concentration, and one placed downstream. They are connected with the control module via CAN and all the information is exchanged through it. Since it is a smart sensor, all the electrical monitoring is performed inside the sensor and only the results are sent to the Engine Control Module (ECM). Each NOx sensor contains a sensing cell, a pumping cell, and a heater. A sample of exhaust gas passes through a diffusion gap between the sensing cell and the pumping cell. The NOx sensor maintains a constant reference voltage across the sensing cell. An electronic circuit within the sensor controls the pump current through the pumping cell in order to maintain a constant voltage in the sensing cell. The amount of current required to maintain the reference voltage in the sensing cell is proportional to the concentration of NOx in the exhaust. The ECM varies the amount of diesel exhaust fluid (reductant) added by varying the reductant injector duty cycle in response to changes in engine exhaust NOx levels. The smart NOx sensors consist of two components, the NOx module and the NOx sensor element that are serviced as a unit. A circuit or performance condition with a NOx sensor is detected by the NOx sensor module. The smart NOx sensor module communicates the condition to the ECM over the serial data line. The ECM sets a DTC when a serial data message is received from the NOx sensor module. The Diagnostic Trouble Code (DTC) will be set if the ECM software detects a fault in the NOx sensor circuitry or a performance fault in the NOx sensor for greater than 2 s.

OBDII Code P1194 2016 GMC Sierra - O2 Low Reference Circuit High Voltage (NOx Sensor 1) - AutoCodes.com — P1194 2016 GMC Sierra Code - O2 Low Reference Circuit High Voltage (NOx Sensor 1)

What does this mean?

What are the Possible Causes of the DTC P1194 2016 GMC Sierra?

Faulty Nitrogen Oxides (NOx) Sensor
Nitrogen Oxides Sensor harness is open or shorted
Nitrogen Oxides Sensor circuit poor electrical connection

How to Fix the DTC P1194 2016 GMC Sierra?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1194 2016 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P1194 2016 GMC Sierra code?

Need more information on how to fix the P1194 2016 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1194 2016 GMC Sierra Code

What does the OBDII code P1194 mean on a 2016 GMC Sierra?

P1194 indicates an issue with the O2 low reference circuit high voltage, typically related to NOx Sensor 1, which monitors nitrogen oxide emissions in the exhaust system.

What are the symptoms of code P1194 in a 2016 GMC Sierra?

Common symptoms include an illuminated check engine light, reduced engine performance, increased emissions, and, in some cases, poor fuel economy.

What causes the P1194 code to appear in a 2016 GMC Sierra?

This code is often caused by a faulty NOx sensor, damaged wiring or connectors in the O2 sensor circuit, or an issue with the vehicleâ€™s engine control module (ECM).

Can a faulty NOx sensor trigger the P1194 code?

Yes, a malfunctioning NOx sensor is a common cause of the P1194 code, as it may send incorrect voltage signals to the ECM.

How do you diagnose the P1194 code on a 2016 GMC Sierra?

Diagnosis involves using a scan tool to read the code, inspecting the wiring and connectors for damage, testing the NOx sensor, and checking the ECM for proper functionality.

Can you drive with the P1194 code active?

While the vehicle may still be drivable, itâ€™s not recommended to ignore the issue, as it can lead to increased emissions, reduced performance, and potential damage to other components.

What is the most common fix for code P1194 on a 2016 GMC Sierra?

The most common fix is replacing the faulty NOx sensor, but repairs may also involve fixing damaged wiring or connectors in the O2 sensor circuit.

How much does it cost to repair the P1194 code on a 2016 GMC Sierra?

Repair costs can vary, but NOx sensor replacement typically ranges from $300 to $800, depending on parts and labor.

Can a software update fix the P1194 code?

In some cases, a software update for the ECM may resolve the issue if the problem is related to incorrect programming or calibration.

How can you prevent the P1194 code from recurring?

Regular vehicle maintenance, including inspecting sensors and wiring, can help prevent this code from recurring. Additionally, addressing any engine issues promptly is crucial.